78Provision as to post office letter boxes
(1)Where it appears to the Postmaster-General that any post office letter box, by reason of being on the premises of any private person or otherwise, is so situated as not to afford the same security against the improper removal of postal packets therefrom or other fraud as exists in the case of other post office letter boxes, he may declare that that post office letter box shall be a private posting box, and shall affix upon or near the box a notice of its being and of the effect of its being a private posting box, and a postal packet put into that box shall not, for the purpose of any enactment, law or contract whereby the due posting of a postal packet is evidence of the receipt thereof by the addressee, be deemed to have been duly posted.
(2)A certificate purporting to be signed by the Postmaster-General or on his behalf by an officer of the Post Office duly authorised by or under section eighty-three of this Act to the effect that any box or receptacle is or was provided by the permission or under the authority of the Postmaster-General for the purpose of receiving postal packets or any class of postal packets, shall in any legal proceedings be sufficient proof of the facts stated in the certificate unless the contrary is shown.